Blaise Pascal died #OTD in 1662. His earliest mathematical work was on
conic sections; he wrote a significant treatise on the subject of
projective geometry at the age of 16. He later corresponded with Pierre
de Fermat on probability theory, strongly influencing the development
of modern economics and social science. In 1642 he started some
pioneering work on calculating machines, establishing him as one of the
first two inventors of the mechanical calculator.